Fans often ask about Diablo 3's system requirements. While Blizzard won't make those known until much closer to the game's launch, we can look at the SC2 minimm requirements for some insight. Here's what Blizzard says, on their B.net support page. [1]

A smaller Starcraft 2 Easter Egg features Deckard Cain's classic "Stay awhile, and listen." line of dialogue as the name of an Achievement. A fan reported on where this achievement was obtained. [2]

This achievement is after you finish the Gates of Hell mission in planet Char. There’s a cinematic right after, then you see an interactive Raynor, General Waterfield and Tychus with a char background. The achievement suddenly pops when that loads. It’s interactive as in you hover the mouse over Raynor, the General and Tychus, and they become silhouette-highlighted, you click them and they have a cutscene-dialogue.

The first and most dramatic is an appearance of a miniature Diablo in a SC2 single-player mission called "The Devil's Playground." Diablo is just a "critter," one of the forms of ambient life, but it's definitely Big Red, though he's small and gloriously burning, the model looks to be the same one used for the World of Warcraft mini-pet.

A screenshot can be seen to the right. See the original news post for more details and a movie of the little guy.

The SC2 collector's edition was released on July 27, 2010, the same day as the regular game. There has not yet been any word about Collector's Editions for SC2 parts 2 and 3. The Diablo III Collector's Edition will not contain the same stuff as the SC2:CE did, but the loot will likely be fairly similar.

The SC2:CE contained:

An art book. (Hardcover, full of concept art for Starcraft II and notes from the artists.)

A 2 GB flash drive modeled after Jim Raynor’s dog tag with the original StarCraft and Brood War expansion preloaded.